/Engine/Plugins/Runtime/Metasound/Source/MetasoundFrontend/Public/MetasoundFrontendDocumentBuilder.h
Builder used to support dynamically generating MetaSound documents at runtime. Builder contains caches that speed up common search and modification operations on a given document, which may result in slower performance on construction, but faster manipulation of its managed document. The builder's managed copy of a document is expected to not be modified by any external system to avoid cache becoming stale.
[USTRUCT](Programming/UnrealArchitecture/Reference/Structs)() struct FMetaSoundFrontendDocumentBuilder